The purpose of adding alloying components is to change the physical properties of steel - increasing strength, resisting corrosion, increasing flexibility. Depending on the concentration of alloying elements, three types are distinguished: low-alloy steel (additional components less than 2.5%), medium-alloy steel (from 2.5 to 10%) and high-alloy steel (from 10 to 50%).
What are the main differences between high-alloy steel? What grades of high-alloy steels exist? And what should you remember when carrying out welding work? Below we will find out the answers to these questions.
Stainless steel: what is alloy steel?
Stainless steel, commonly called “stainless steel,” is resistant to corrosion and contains alloying elements.
The term “alloyed” means the inclusion of iron-carbon alloying elements in an alloy to improve the properties of the metal. Depending on these additives, stainless steel receives certain physical, chemical or mechanical properties. Stainless steel has great value in manufacturing. Ukraine occupies a worthy position in the global stainless steel market. Ukrainian metal rolling produces metal for certain areas, which reduces its cost, but at the same time does not harm quality.
The company https://steelservice.com.ua/ offers its partners stainless steel products from the best global and Ukrainian manufacturers. A wide range of products is presented to customers. Qualified advice on choosing the composition and form of rolled products and a competitive price for stainless steel in full compliance with all quality standards will help you find everything you need in our company.
Chromium is the main alloying agent; its content in the alloy can vary from 12 to 20%. The structural state of steel depends on its percentage. And its resistance to corrosion is assessed first of all.
When interacting with oxygen, chromium forms an invisible thin and dense layer on the surface of the metal, which is called an oxide film. It is this that protects the metal from direct exposure to the external environment and protects it from chemical attack. The minimum permissible amount of chromium, which gives stainless steel corrosion resistance to weathering and most industrial agents, in high-alloy steels is 12%. 17% or more percent of chromium allows the metal to be resistant to alkalis, salts, acids, sea water and soil.
It is worth noting that adding other metals to the structure of stainless steel makes it less homogeneous, but at the same time improves some quality characteristics. In addition to chromium, titanium, nickel, copper, molybdenum, etc. can be added to the steel composition. For example, titanium increases the scale resistance of steel - resistance to oxidation at high temperatures. Nickel makes steel more ductile, harder and increases its mechanical strength. The high nickel content alloy can be polished to a mirror finish. The addition of copper and molybdenum gives the metal elasticity and tensile strength. You can increase the heat resistance of stainless steel by adding aluminum and silicon to it. Cobalt makes it hard and durable, and tungsten alloying gives the steel excellent cutting properties and increases its wear resistance.
Thanks to this, elements, components, parts, pipes made of stainless steel can be used for decades in conditions under which other materials become not only aesthetically unattractive, but also cease to meet sanitary requirements.
The use of corrosion-resistant steels
Highly alloyed material with anti-corrosion coating is used in alkaline acids and gas environments. In such metals the carbon content is approximately 0.12%. Subsequent heat treatment and alloying make it possible to produce an alloy with unique properties that is not susceptible to exposure to liquid metal and gas environments.
The use of steels with the addition of boron, molybdenum and tungsten allows work to be carried out even at temperatures above 1000 degrees Celsius. Molybdenum and tungsten are strengthening agents. To increase the scale resistance of products, aluminum and silicon can be added. Structures made in this way are often used in furnaces as heating elements.
Alloying Additives Mission
High alloy steels contain:
- carbon;
- silicon (provides elasticity);
- manganese (provides hardness);
- titanium (promotes the removal of nitrogen and the formation of a dense structure, is responsible for heat resistance);
- molybdenum (affects heat resistance);
- vanadium (strengthens the structure);
- tungsten (prevents grain growth, strengthens the molecular lattice);
- cobalt (increases mechanical strength).
In steels of this group, the content of sulfur, aluminum, phosphorus, boron, niobium, and copper is permissible.
High-alloy special steels and alloys are classified according to their structure into:
- martensitic and austenitic-martensitic;
- ferritic and austenitic-ferritic;
- austenitic.
In terms of properties, consumers are interested in:
- heat resistant;
- heat resistant;
- stainless (corrosion resistant).
The table below provides information about well-known grades of high-alloy steels and describes the chemical composition.
Description of metal
First you need to find out what this metal alloy is. So, this material is essentially an alloy of carbon and iron containing special elements that affect the physical and mechanical characteristics of the finished product. The components added to it are called alloying components. Copper, vanadium, manganese, nickel and chromium are the most common ones.
Types of alloy steel
Alloyed metal is classified according to the percentage of alloying elements in its composition:
- low alloy alloy - up to 2.5%;
- medium alloyed - from 2.5 to 10%;
- highly alloyed - from 10 to 50%.
There is another important point to consider. High-alloy steel and alloys based on it have their own classification and characteristics, and can also be used under different conditions:
- heat-resistant (heat-resistant) steels;
- resistant to corrosion.
Based on the type of alloying components, it is customary to distinguish the following types of alloys:
- chromium-nickel;
- chromomanganese;
- chromium.
Features of use
Alloy steels are simply irreplaceable in the production of a whole range of products. The following areas of activity cannot do without this metal and alloys based on it:
- automotive industry;
- construction;
- chemical production;
- oil and gas industries.
The inclusion of alloying elements in the metal composition allows one to achieve unique mechanical characteristics of the material. Therefore, high-alloy steel alloys are used as a cold-resistant component.
Application of high alloy steel
The metallurgy of special steels is developing. Rolled metal and structures made from high-alloy alloys are distinguished by special characteristics; they are planned to be purchased for work in extremely aggressive environments.
Experts note the greatest demand for products of this difficult rank in the oil and chemical industries, energy, and mechanical engineering.
Our company, cooperating with large Russian factories, sells rolled products made from various raw materials, including structural, alloyed and high-alloy alloys.
We guarantee low prices, will gladly accept orders and deliver purchases to addresses in St. Petersburg, Leningrad region, and regions.
Types and brands
The first classification involves 3 divisions: heat-resistant, scale-resistant and corrosion-resistant. Heat-resistant high-alloy steels differ from heat-resistant steels, for example, in that products made from them can be used for some time at high thermal indices of the external environment and under load. Corrosion-resistant steels are often called stainless steels. And they are truly resistant to different types of corrosion: salt, acid, alkaline, chemical. This also includes intergranular corrosion, atmospheric and associated with electrical voltage.
Finally, scale-resistant steels are heat-resistant. They are used in an unloaded state or in a lightly loaded state. They are highly resistant to chemical deformation associated with the surface layer when the temperature of the external gaseous environment is above 550 degrees.
The classification also includes magnetic and non-magnetic alloys. The former are soft magnetic and hard magnetic. So the statement that stainless steel is a non-magnetic material is very controversial.
Concluding the list of characteristics, one cannot fail to mention the division of steels into the following types:
- mass – these are pipes, sheet and shaped products;
- bridge construction - used for cars and bridges;
- shipbuilding cold-resistant high strength - for welded structures that will operate at low temperatures;
- shipbuilding cold-resistant normal and increased strength - this is steel that resists destruction well;
- for steam and hot water – steel with an operating temperature of up to 600 degrees;
- low-low, high strength - a material used in aviation, but it is afraid of stress concentration.
It would be fair to note the importance of alloying components. They can be considered the basis, the main ingredient of the composition, which decides where the material will be used more effectively later.
Martensitic
The list of other types opens with martensitic grades, in which the amount of carbon is up to 0.7%, chromium is approximately 8-19%, and there is also some silicon and manganese. An example of such a brand is 30X13.
Ferritic
There is very little carbon in such steels - up to 0.15%, but there is much more chromium - up to 30% at maximum, and there will be a lot of silicon, manganese or titanium in the steel. An example of this type is 15Х25Т.
Austenitic
These are grades with a very low percentage of carbon, a moderate presence of chromium, varying concentrations of nickel (can reach up to 25%) and manganese (from 1 to 14%). There may be very little nitrogen and silicon there. An example of this class is 20Х25Н20С2.
Composite austenitic-martensitic
Carbon here ranges from 0.1 to 1%, there is quite a lot of chromium - on average 16%, there may be quite a bit of titanium, silicon and aluminum. Example - 08Х17Н6Т.
There are brands that are most suitable for making tableware. For example, 12X17. But in general, we can say that high-alloy steels are more than actively used in many industries, and the scope of their application is definitely only expanding.
Properties of certain types of high-alloy steels
Due to their unique characteristics, which can be formed by changing the chemical composition of the alloy, steels with a high content of alloying additives have found wide application in almost all sectors of modern industry. Among the wide variety of types of high-alloy alloys, the most widely used are steels whose internal structure is based on austenite. The basic elements of the chemical composition of such steels are nickel, which they contain at least 8%, as well as chromium, the content of which exceeds 18%. By varying the amount of other alloying additives in the composition of such steels, grades of alloys with the required characteristics are obtained.
Chemical composition of some alloy steels
Heat-resistant steels, which additionally contain tungsten and molybdenum (up to 7%), as well as boron, which is necessary to refine the grain of their internal structure, do not change the original mechanical characteristics even after being in a heated state for a long time.
A distinctive feature of high-alloy steel grades classified as corrosion-resistant or stainless steel is the low carbon content in their chemical composition (up to 0.12%). Such steels, in addition to alloying with appropriate additives, are subjected to special heat treatment. Thanks to this technological technique and the properties of the elements that form the composition of steels, they become very resistant to aggressive environments: acidic, salt, alkaline, gas, etc.
The influence of alloying elements on the properties of steel
Heat-resistant steels, which are able to withstand elevated ambient temperatures in an unloaded state, obtain their properties due to the fact that aluminum (up to 2.5%) and silicon are additionally introduced into their composition, due to which dense and durable materials are formed on the surface of products made from such alloys. oxides Such oxides become a kind of film that reliably protects the surface of the steel product from interaction with a heated gas environment.
In order to form the required mechanical characteristics (strength and ductility) of products made from high-alloy steels, they are subjected to special heat treatment, which consists of two stages:
- hardening, which involves heating the alloy to a temperature of 1150 degrees and its subsequent rapid cooling in water;
- stabilizing tempering, which involves heating high-alloy steel to a temperature of 850 degrees and its subsequent cooling in the open air to room temperature.
The final properties of a product made from a certain grade of high-alloy steel depend both on its chemical composition and on the modes and types of heat treatment used.
High alloy structural steel
Properties of alloy steel
The properties of alloy steels are varied. They are mainly determined by those additives that are used as alloying agents in the production of certain types of steel materials.
Depending on the added alloying components, steel acquires the following qualities:
- Strength. This property is acquired after adding chromium, manganese, titanium, and tungsten to its composition.
- Resistant to corrosion. This quality appears under the influence of chromium and molybdenum.
- Hardness. Steel becomes harder thanks to chromium, manganese and other elements.
Attention: It is worth noting that in order for alloy steel to be more durable and resistant to external environmental influences, the required chromium content should not be less than twelve percent.
Alloy steel, with the correct percentage of all elements included in it, should not change its quality when heated to temperatures up to six hundred degrees Celsius.
Production of alloy steel.
Areas of application of products
The most popular brands of high-alloy alloys, belonging to different classes according to their structure, include:
- martensitic, which is characterized by the following chemical composition: chromium - 8-19%, manganese - no more than 1.2%, silicon - 0.6-3%, carbon - 0.12-0.7%; these are 07Х16Н4Б, 20Х17Н2, 65Х13, 13Х11Н2В2МФ, 25Х13Н2, 20Х17Н2, 11Х11Н2В2МФ, 40Х10С2М, 30Х13, 15Х11МФ, 40Х9С2, etc.;
- ferritic alloys, characterized by the following composition: chromium - 12-30%, manganese - up to 0.8%, silicon - 0.8-2%, carbon - 0.07-0.15%; these are 08Х18Тч, 12Х17, 15Х28, 10Х13СУ, 15Х25Т, 08Х17Т, 08Х13, etc.;
- martensitic-ferritic, having the following chemical composition: chromium - 11-18%, manganese - 0.5-0.9%, silicon 0.4-0.8%, carbon - 0.12-0.22%; these are 12Х13, 14Х17Н2, 15Х12ВНМФ, etc.;
- austenitic-martensitic, the composition of which contains: chromium - 14-18%, manganese and silicon - up to 0.8%, carbon - 0.05-0.9%; these are 07Х16Н6, 08Х17Н5М3, 08Х17Н6Т, 09Х15Н8У1, etc.;
- austenitic-ferritic, containing the following elements: chromium - 19-25%, manganese - 0.5-9%, silicon - 0.8-4.5%, carbon - 0.08-0.2%; these are 15Х18Н12С4ТУ, 12Х21Н5Т, 03Х22Н6М2, 03Х23Н6, etc.;
- austenitic, which includes: chromium - 10-19%, nickel - 2.8-25%, manganese - 0.6-15%, silicon - 0.4-0.8%, carbon - 0.05-0 .21%; these are 12Х18Н12Т, 20Х25Н20С2, 31Х19Н9МВБТ, 45Х14НМВ2М, 08Х10Н20Т2, 12Х25Н16Г7АР, etc.
To understand how important steels with a high content of alloying elements are in modern industry, we can give examples of the areas of application of individual grades of such alloys.
The popular grade 12X17 steel is widely used for the production of kitchenware and household items. A limitation of the use of such steel is that products made from it cannot be joined by welding.
Physical characteristics of steel grade 12Х17
High-alloy steel grades 12Х13, 08Х13 and 20Х13 are used to make parts of hydraulic devices, products that are subjected to shock loads during operation and operating in mildly aggressive environments.
Steel grade 95X18 has excellent wear resistance, so ball bearing elements for critical installations, bushings, knives and other tools are made from it. 30Х13 and 40Х13 are grades of high-alloy steels, from which compressor valve plates, parts of automobile carburetors, springs for various purposes, measuring and medical instruments are made.
This is just a small list of applications in which it is simply impossible to do without the use of high-alloy steels due to their unique characteristics.
Low-alloy steel, high-quality structural
Regulatory document: high-quality structural low-alloy steel is manufactured in accordance with GOST 19281-89.
Low-alloy steel - alloy steel with a total mass of alloying elements less than 2.5% of the total mass of steel.
Low alloy steel grades
Steel grades: 09G2, 09G2S, 0KHSND, 17G1S, 16G2AF, 10KHNDP, 15KHNDP, 0KHSND, 15KHSND, etc.
Low-alloy steel grades 10KhNDP, 15KhNDP, 0KhSND, 15KhSND are atmospherically corrosion-resistant (AKS).
Substitutes for some grades of steel:
- 09G2S - 09G2, 09G2DT, 09G2T, 10G2S;
- 10HSND - 16GAF.
Application of low alloy steel
Low-alloy steel is used for the manufacture of railway, metro and tram car bodies, load-bearing structures of locomotives, agricultural and other field machines and engineering structures operating under conditions of variable dynamic loads and seasonal and daily heat changes.
Weldability: low-alloy steel can be welded without restrictions.
Characteristics of alloy steels
Alloy steel is steel that, in addition to the usual impurities, is also equipped with additional additives that are necessary for it to meet certain chemical and physical requirements.
Ordinary steel consists of iron, carbon and impurities, without which it is impossible to imagine this material. Additional substances are added to alloy steel, which are called alloying substances. They are used to ensure that steel has the properties that are necessary in certain situations.
In most cases, the following are added to iron, impurities and carbon as alloying elements: nickel, niobium, chromium, manganese, silicon, vanadium, tungsten, nitrogen, copper, cobalt. It is also not uncommon for such materials to contain substances such as molybdenum and aluminum. In most cases, titanium is added to add strength to the material.
This type of steel has three main categories. The relationship of alloy steel to a particular group is determined by how much steel and impurities it contains, as well as alloy additives.
Types of Alloy Steel
There are three main types of steel with alloying elements:
It is characterized by the fact that it contains about two and a half percent of alloying additional elements.
This material contains from 2.5 to 10 percent of additional alloying substances.
This type includes steel materials, the amount of alloying additives in which exceeds ten percent. The amount of these components in such steel can reach fifty percent.
Purpose of alloy steel
Alloy steel is widely used in modern industry. It has a high level of strength, which allows it to be used to manufacture equipment for cutting and chopping rolled metal of various types.
According to their purpose, alloy steels can be represented by a large number of groups.
The main ones are:
- structural alloy steel,
- tool alloy steel,
- alloy steel with special chemical and physical properties.
The characteristics of alloy steels can be varied. They acquire them due to the ratio of the basic elements. Steels of this type are in any case more durable and resistant to corrosion.
Alloy steel marking
According to GOST, for marking alloy steel (low-, medium- and high-alloy) special codes are used that display the approximate composition of a particular grade. In a technical sense, ciphers have the form of an alphanumeric sequence, which has the following structure: XXXYYYZZZ (all characters are written together and without deviations). The decoding of the code is as follows:
- XXX is a special letter prefix that indicates the type of steel alloy (we will give the decoding below).
- YYY - This fragment is a number that represents the amount of carbon in the alloy. If there are two numbers, this means that the carbon content is expressed in hundredths of a percent. If there is one number, the carbon content is in tenths of a percent.
- ZZZ is an alphanumeric sequence that displays alloying components and their approximate quantity (we will also give a decoding below).
Decoding
Let's now look at the XXX prefix - this code indicates the special properties of steel. In a technical sense, it represents one or more letters (most often one) that denotes a particular property. The XXX prefix has almost fallen into disuse and is rarely used in practice. The main values that the prefix can take are presented in the table below:
| Prefix character XXX | Prefix decoding |
| E | Electrical steel |
| A | Automatic steel |
| R | Cutting steel |
| L | Cast steel |
The ZZZ sequence indicates the presence of additional alloying components in the steel alloy. If any component in a steel alloy is contained in a concentration of more than 1%, then the percentage of this element is indicated next to the letter. The letters are deciphered as follows:
| ZZZ value | Decoding |
| X | Chromium |
| N | Nickel |
| WITH | Silicon |
| IN | Tungsten |
| M | Molybdenum |
| F | Vanadium |
| YU | Aluminum |
| G | Manganese |
| TO | Cobalt |
| T | Titanium |
All this sounds quite intimidating, but there is nothing complicated about it. Let's try to decipher several popular grades of high-alloy steel:
- А10Х13СУ - free-cut steel, which contains 0.10% carbon, 13% chromium, as well as silicon and aluminum in a concentration of less than 1%
- L12X17 - cast steel, which contains 0.12% carbon and 17% chromium.
- 12Х18Н12Т - steel that contains 0.12% carbon, 18% chromium, 12% nickel, as well as titanium in a concentration of less than 1%.
Alloy steel grades
Alloy steel grades vary. They are presented in a wide variety. Depending on the purpose of the steel, its marking is determined.
Today there are a large number of requirements for marking alloy steel. Numerical and alphabetic notations are used for this process. First, numbers are used for marking. They are indicators of how many hundredths of carbon are contained in a particular type of alloy steel. After the numbers there are letters, which indicate which alloying additives were used in the production of a particular type of alloy steel.
The letters may be followed by numbers indicating the amount of alloying substance in the steel material. If there is no digital designation after the designation of any alloying element, then it contains a minimum amount of it, not reaching even one percent.
Table 1. Comparison of steel grades of type Cm and Fe according to international standards ISO 630-80 and ISO 1052-82.
Steel grades
| St | Fe | St | Fe |
| One hundred | Fe310-0 | St4kp | Fe430-A |
| St1kp | St4ps | Fe430-B | |
| St1ps | St4sp | Fe430-C | |
| St1sp | — | — | Fe430-D |
| St2kp | St5ps | Fe510-B, Fe490 | |
| St2ps | St5Gps | Fe510-B, Fe490 | |
| St2sp | Sg5sp | Fe510-C, Fe490 | |
| StZkp | Fe360-A | ||
| StZps | Fe360-B | St6ps | Fe590 |
| StZGps | Fe360-B | Stbsp | Fe590 |
| StZsp | Fe360-C | Fe690 | |
| StZGsp | Fe360-C | — | |
| Fe360-D |
Table 2. Symbols of alloying elements in metals and alloys
| Element | Symbol | Designation of elements in grades of metals and alloys | Element | Symbol | Designation of elements in grades of metals and alloys | ||
| black | colored | black | colored | ||||
| Nitrogen | N | A | — | Neodymium | Nd | — | Nm |
| Aluminum | A1 | YU | A | Nickel | Ni | — | N |
| Barium | Va | — | Br | Niobium | Nb | B | Np |
| Beryllium | Be | L | Tin | Sn | — | ABOUT | |
| Bor | IN | R | — | Osmium | Os | — | OS |
| Vanadia | V | f | To you | Palladium | Pd | — | front |
| bismuth | Bi | In and | In and | Platinum | Pt | — | Pl |
| Tungsten | W | IN | — | Praseodymium | Pr | — | Etc |
| Gadolinium | Gd | — | Gn | Rhenium | Re | — | Re |
| Gallium | Ga | Gi | Gi | Rhodium | Rh | — | Rg |
| Hafnia | Hf | — | Gf | Mercury | Hg | — | R |
| Germanium | Ge | — | G | Ruthenium | Ru | — | Pv |
| Holmium | But | — | GOM | Samarium | Sm | — | Myself |
| Dysprosium | Dv | — | DIM | Lead | Pb | — | WITH |
| Europium | Eu | — | Ev | Selenium | Se | TO | ST |
| Iron | Fe | — | AND | Silver | Ag | — | Wed |
| Gold | Au | — | Evil | Scandium | Sc | — | From km |
| Indium | In | — | In | Antimony | Sb | — | Cv |
| Iridium | Ir | — | AND | Thallium | Tl | — | Tl |
| Ytterbium | Yb | — | ITN | Tantalum | Ta | — | TT |
| Yttrium | Y | — | THEM | Tellurium | Those | — | T |
| Cadmium | Cd | CD | CD | Terbium | Tb | — | Volume |
| Cobalt | Co | TO | TO | Titanium | Ti | T | TPD |
| Silicon | Si | WITH | Kr(K) | T\'liy | Tm | — | TUM |
| Lanthanum | La | — | La | Carbon | WITH | U | — |
| Lithium | Li | — | Le | Phosphorus | P | P | F |
| Lutetium | Lu | — | Leung | Chromium | Cr | X | X(Xp) |
| Magnesium | Mg | Sh | Mg | Cerium | Ce | — | Xie |
| Manganese | Mn | G | Mts(Mr) | Zinc | Zn | — | C |
| Copper | Cu | D | M | Zirconium | Zr | C | TsEV |
| Molybdenum | Mo | M | — | Erbium | Er | — | Erm |
Main characteristics of the metal
High-alloy steel has properties and characteristics that allow the products to be used more widely. Such steels have the following characteristics:
- Strength (achieved through heat treatment).
- Corrosion resistance.
- Resistance to deformation processes.
- Plasticity (compared to carbon steel, ductility is many times greater).
- Nonmagneticity (steels used in mechanical engineering).
- Elasticity.
- Hardening.
- Weldability.
Due to the fact that the alloy formula is different, the properties are varied. The structure is easily changed due to heat treatment and alloying components. In this way, it is possible to obtain the properties required by the project conditions. For example, high-alloy 18% chromium steel may contain nickel, which makes it possible to obtain corrosion resistance and cold brittleness.
Welding high-alloy steels allows us to obtain products that can be used in any climatic conditions. Thus, the stamp-welding method allows the final product to be used at critically low temperatures - down to minus 253 degrees Celsius. Special treatment with silicon makes it possible to obtain ferrosilides that can work in strong acids (nitric, phosphoric and others).
High-alloy steel is hard and highly abrasive. Thus, acid-resistant materials are C15 and C17, and chromium, vanadium and manganese increase the wear resistance of the alloy.
Manual arc welding technology
Preparation for welding:
- The edges of the welded products are prepared mechanically . Cutting by plasma, gas-flux or electric arc methods is also allowed. When using fire types of cutting, mechanical processing of the edges to a depth of 2-3 mm is necessary.
- The type of edge joint depends on the thickness of the products . With a thickness of more than 4 mm, the chamfer is removed at an angle of 45°, and with a thickness of more than 8 mm, the chamfer is removed at an angle of 30°. With thicknesses of joined products up to 10 mm, the gap between the edges is 1 mm, and for larger thicknesses the gap can be increased to 1.5-2.5 mm.
- After chamfering, the welded edges are cleaned of scale by 20 mm and degreased.
- The joints are assembled using standard fixtures or tacks . The quality of tack welds is subject to the same requirements as the weld seam. You cannot place tacks where seams intersect.
Equipment
When performing manual electric arc welding, the following equipment is used:
- welding machine;
- welder hand tool;
- devices.
The welding machine includes a power source to create an electric arc. A special feature of the equipment for welding high-alloy steels is that it is produced by direct current with reverse polarity. Therefore, a DC generator or a rectifier (inverter) can serve as a power source for such welding.
A DC generator produces DC voltage by converting mechanical energy into electrical energy. A rectifier typically includes a step-down transformer and a semiconductor circuit that converts alternating current to direct current. Inverters are often used as a DC source. In such devices, double conversion of electricity is performed, which makes it possible to obtain a more stable output voltage.
Approximate cost of inverter power sources on Yandex.market
In addition to the power source, the welding machine includes a control panel, connecting wires, a welding electrode, and a screw or clamp-type electrode holder.
As equipment, the welder uses a protective mask that filters UV and IR radiation from the arc, a respirator to protect the respiratory system and special clothing.
The hand tool set includes a hammer, chisel, wire brush, and a bag for carrying tools and electrodes.
Welding process
The main feature of welding high-alloy steels is the requirement for low heat input into the base material.
This requirement is achieved through:
- Short arc.
- No lateral vibrations.
- High speed of movement of the welding arc without interruptions and repetition of heating of the same place.
- Using the lowest possible current modes.
There are special tables for selecting the current mode. For example, for welding austenitic steels up to 2 mm thick with an electrode with a diameter of 2 mm, a welding current of 20 to 50 A is recommended, and for welding parts with a thickness of 8 to 12 mm with a 4-5 mm electrode, the welding current should be about 85-160 A.
At the beginning of arc welding, the edges are heated and a weld pool is formed. Next, the arc is evenly moved along the joint. In this case, it is necessary to monitor the depth of penetration and the absence of lack of penetration. The quality of welding can be judged by the shape of the weld pool. If it is elongated in the direction of arc movement, then the penetration is good. If the welding quality is poor, the pool has the shape of a circle or oval.
High alloy steel grades
The most popular and well-known steel grades are:
- Ferritic: 15Х28, 12Х17, 08Х18Т1, 15Х25Т, 08Х18Тч, 10Х13СУ.
- Martensitic: 15Х11МФ, 40Х9С2, 18Х11МНФБ, 40Х10С2М, 95Х18, 25Х13Н2, 20Х17Н2, 13Х11Н2В2МФ, 40Х13, 20Х13, 20Х17Н2, 13Х14Н3В2ФР.
- Austenitic-martensitic: 07Х16Н6, 08Х17Н5М3, 08Х17Н6Т, 09Х17Н7У1.
- Austenitic-ferritic: 08Х21Н6М2Т, 08Х22Н6Т, 08Х20Н14С2, 20Х23Н13, 12Х21Н5Т, 03Х22Н6М2.
- Martensitic-ferritic: 12Х13, 18Х12ВМБФР, 14Х17Н2, 15Х12ВНМФ.
- Austenitic: 05Х18Н10Т, 45Х22Н4М3, 45Х14НМВ2М, 10Х14Г14Н4Т, 03Х18Н10Т, 08Х16Н13М2Б, 12Х18Н12Т, 03Х18Н12, 03Х16Н15М3Б, 10Х11Н23Т3МР , 20Х23Н18, 10Х11Н20Т2Р, 12Х18Н9Т, 12Х18Н9, 20Х25Н20С2.
Application of alloying steel grades:
- 40Х13, 30Х13 – used for carburetor needles, springs for transport, surgical instruments.
- 12X17 is a grade of high-alloy steel used for the manufacture of kitchen utensils and household items.
- 20Х13, 12Х13, 08Х13 – used for the manufacture of elements of hydraulic installations and structures that operate in slightly aggressive conditions.
- 95Х18 – used for the production of high-hard ball bearings.
Decryption procedure
Positions in the notation, from left to right.
- 1st – C (carbon) content, expressed in hundredths of a percent.
- 2nd – chemical element providing alloying.
| Aluminum | Al, Yu | Copper | Cu, M | Vanadium | V, F |
| Chromium | X | Nitrogen | N, A | Tungsten | W, V |
| Niobium | Nb, B | Bor | V, R | Silicon | Si, C |
| Zirconium | Zr, C | Cobalt | Co, K | Tantalum | Ta |
| Selenium | Se, E | Iron | Fe, F | Titanium | Ti, T |
| Nickel | Ni, N | Molybdenum | Mo, M | Manganese | Mn, G |
3rd – percentage of alloying additive in steel. If it is equal to or less than 1, then the number is not entered.
Examples of marking of high-alloy steels
8Х18Н10Т – carbon (0.08), chromium (18), nickel (10), titanium (1).
38Х12МУА – carbon (0.38); chromium (12); molybdenum and aluminum - 1% each. The last letter (A) indicates the high quality of the steel.
As already noted, the division of high-alloy steels into groups (austenitic, martensitic, and so on), the specifics of application (tool, structural) are described in GOST and do not directly relate to the topic of the article. And the author has already explained in detail how to “read” the markings correctly.
What properties do alloying elements impart to steel?
Many of the additives are similar in their effect on the material. For example, they increase its strength and corrosion resistance. Therefore, we note only those characteristics of steel on which a specific additive has the maximum impact. That is, it significantly improves them.
- Titanium – heat resistance; also promotes compaction of the structure by removing excess nitrogen.
- Cobalt – mechanical strength.
- Vanadium, tungsten, molybdenum - prevent grain growth and contribute to the invariability of the structure of high-alloy steel. Its cutting ability increases. In addition, Mo has a positive effect on the heat resistance of the material.
- Nickel – increases elasticity and rust resistance.
- Chromium – imparts many properties. In addition to those listed above, it ensures that steel is not susceptible to abrasion and its high-quality calcination.
- Manganese – hardness. However, as the temperature increases, the grain increases in size. This has a negative impact on impact strength.
- Silicon – gives steel elasticity.
One of the features of processing high-alloy steels is their hardening technology. It is produced not in water, but in oil.
Types of alloy steels
The main classification divides all brands into three subtypes according to the amount of useful impurities. Let's present the percentage in the table:
| Name | Additive percentage |
| Low alloy | About 2.5%. Positive qualities have increased, but malleability and other characteristics for metalworking have not changed much. |
| Medium alloyed | From 2.5% to 10%. This connection is used most often. |
| High alloy | From 10% to 50%. Maximum strength and high cost are the distinctive features of such products. |
In addition, all common alloy steels differ by grade. We will talk about this in more detail in the section on labeling.
Classification
Regardless of the percentage of alloying substances in the alloy, it can also be divided into three subtypes:
- Structural – used for the manufacture of various parts, mechanisms and structures in mechanical engineering, machine tool building, other areas of industry and construction. This is a very durable material that can withstand large static and dynamic loads. It is from these brands that engines and spare parts for cars are made.
- Tool - very heat-resistant, which is intended for creating tools - both manual and machine tools. Most milling cutters, cutters, and drills are made of this kind of steel.
- With special properties. If the previous two varieties were more likely to be considered for their strength and reliability, then this subspecies is characterized by chemical or thermal resistance.
A number of researchers even classify the last category separately, arguing that it can be divided into:
- Heat resistant - they can withstand temperatures up to 1000 degrees.
- They are resistant to metal corrosion, so they can be used in products and structures that are intended for use in conditions of high humidity.
- Heat-resistant and scale-resistant - characteristics indicate their immunity to decay.
Examples of marking of high-alloy steels
8Х18Н10Т – carbon (0.08), chromium (18), nickel (10), titanium (1).
38Х12МУА – carbon (0.38); chromium (12); molybdenum and aluminum - 1% each. The last letter (A) indicates the high quality of the steel.
As already noted, the division of high-alloy steels into groups (austenitic, martensitic, and so on), the specifics of application (tool, structural) are described in GOST and do not directly relate to the topic of the article. And the author has already explained in detail how to “read” the markings correctly.
What properties do alloying elements impart to steel?
Many of the additives are similar in their effect on the material. For example, they increase its strength and corrosion resistance. Therefore, we note only those characteristics of steel on which a specific additive has the maximum impact. That is, it significantly improves them.
- Titanium – heat resistance; also promotes compaction of the structure by removing excess nitrogen.
- Cobalt – mechanical strength.
- Vanadium, tungsten, molybdenum - prevent grain growth and contribute to the invariability of the structure of high-alloy steel. Its cutting ability increases. In addition, Mo has a positive effect on the heat resistance of the material.
- Nickel – increases elasticity and rust resistance.
- Chromium – imparts many properties. In addition to those listed above, it ensures that steel is not susceptible to abrasion and its high-quality calcination.
- Manganese – hardness. However, as the temperature increases, the grain increases in size. This has a negative impact on impact strength.
- Silicon – gives steel elasticity.
One of the features of processing high-alloy steels is their hardening technology. It is produced not in water, but in oil.
Alloy steel - grade - Great Encyclopedia of Oil and Gas, article, page 1
Alloy steel - grade
Page 1
Alloy steels of grades 20KhGSA, 25KhGSA and ZOKHGSA are used for the manufacture of critical stamped and welded parts. Steel 25KhGSA in the annealed state has good ductility and good weldability; after stamping and heat treatment, a strength of about 1300 MPa is provided. ZOKHGSA steel in the annealed state has satisfactory stampability and weldability, and after stamping it is processed to a strength of 1400 MPa. High-strength steel grade ZOKHGSN2A is similar in formability to steel grade ZOKHGSA. It is used for the manufacture of the most critical parts. [1]
Alloy steel 2GM differs from steel 15M in having a slightly higher carbon content. [2]
Alloy steel grade 12МХ is a variety of steel 15М, differing from the latter in containing 0-5% chromium. The main advantage of 12МХ steel compared to 15М molybdenum steel is that, under the influence of the addition of 0–5% chromium, its sensitivity to graphitization is eliminated. However, this additional alloying does not impair the technological properties of steel. Pipes made from 12MX steel retain the ability to be hot bent and have good weldability. Steel 12MX has sufficient stability of properties at 480 - 540 C and is not prone to thermal brittleness. This steel is intended for high-pressure steam pipelines at temperatures up to 500 - 510 C, as well as for steam superheating pipes. In table 74 provides data on the relaxation resistance of steel at 450 C, which can be used in the calculation of elastic elements made from this steel. [3]
Alloy steel grade 25Kh2MFA is one of the most heat-resistant steels. By changing the tempering mode, you can significantly vary the level of mechanical properties. [4]
Soviet alloy steel grades 15M and 20M contain about 0.5% molybdenum, and steel 15 XM contains about 1% chromium and 0.5% molybdenum. [5]
For alloy steel grades 18ХНВА, 40ХФ, 35ХНЗМ (forgings of gears, shafts and disks), the full annealing mode is also used. [6]
Alloy steel grade 18ХГТ is used to make primary and intermediate shafts of gearboxes, gears of 3rd and 5th gears, universal joint crosspieces and a number of other parts. Steel grade 18ХНВА is used for rear axle gears and gearboxes of passenger cars. Steel grade 12Х2Н4А is also used for gears of gearboxes, rear axle and kingpins. Steel grades 60С2, 55С2 are used for the manufacture of springs. [7]
Experimental alloy steel grade HY130/150 has already been mastered, which has a yield strength of 9140 kg/cm2, is easily welded and machined. [8]
Forgings made from alloy steel grade 16M are allowed for parts operating at a temperature not exceeding 475 C, from steel grade 12 ChKh - at a temperature not higher than 540 C, and from steel grade 15ХМ - not higher than 550 C. [9]
Manufactured from alloy steel grades 9Х and 9ХС and high-speed steel EI262 with ground threads. [10]
When etching alloy steel grade OX13Yu, solutions containing nitric and hydrofluoric acids are used. [eleven]
Forgings made from alloy steel grade 16ХМ are allowed for parts operating at a temperature not exceeding 560 C, from steel grade 12ХМ - at a temperature not exceeding 540 С, and from steel 12ХМ - not higher than 560 С. [12]
When welding thermally hardenable alloy steels of grades 12Х1МФ, 15Х1МФ, 12Х2МФСС, under the influence of the thermal cycle of welding, either quenching can occur with the formation of structures of increased hardness, or hardening to martensite. When choosing welding modes for such steels, one strives to avoid sudden hardening and overheating of the metal in the heat-affected zone. But in any case, when welding thermally hardenable steels, a hard, brittle layer is formed. Due to intense heat removal, a bainite structure is formed and the hardness increases. Around point 4, the metal is released and the hardness decreases. In the area beyond point 5, which was heated during welding to no higher than 600 C, the influence of the thermal cycle of welding is small and the hardness remains at a level close to the original one. [14]
The mandrels are made of alloy steel grade ОХН2Ф or Х5М, turned on a centerless grinding machine. To harden their surface, mandrels are subjected to transverse rolling on a special two-roll cross-helical rolling mill in several passes, preheated in a furnace to 750 - 800 C. [15]
Pages: 1 2 3 4
www.ngpedia.ru
Application of alloy steel
There are so many areas of use that it is difficult to list them. Let's just talk about some of the industries:
- Medical instruments, including sharp cutting objects.
- Blades.
- Bearings and other parts with high radial and support loads.
- Cutters, milling cutters, drills and other equipment for metalworking machines.
- Housings for equipment and devices.
- Stainless steel utensils - buckets, basins, etc.
- Made for the automotive industry.
This and much more can be made from this substance. Any task that requires superior strength properties can count on alloy steel.
Properties
Depending on the alloying components, they may vary, but in general the following characteristics are improved:
- Corrosion resistance. Sometimes it is enough just to treat the top layer with a protective compound, but what about parts that are constantly in contact with moisture and oxygen? The answer is simple - dope.
- Strength.
- Hardness.
- No fragility.
- Resistant to tensile and compressive loads.
- The desired level of viscosity and yield strength.
- Reducing magnetization.
Production
The main method is metallurgical. During this process, the required amount of impurities is added to the molten metal. Then additional conditions are set in which diffusion or other reactions occur at a higher rate.
The second option for doping is applying a surface layer in such a way that the substances begin to penetrate each other.
Sources
- https://kuban-stan.ru/drugoe/vysokolegirovannaya-stal-eto-nerzhavejka-ili-net.html
- https://tk-metal.ru/stal/visokolegirovannaya-stal-marki-kharakteristiki-primenenie.html
- https://stroy-podskazka.ru/stal/vysokolegirovannaja/
- https://elton-zoloto.ru/metalloobrabotka/chto-takoe-vysokolegirovannaja-stal.html
- https://FB.ru/article/253463/vyisokolegirovannaya-stal-opisanie-tehnologiya-svarki-markirovka-i-osobennosti
- https://www.rocta.ru/info/legirovannaya-stal-chto-ehto-takoe-marki-sostav-vidy-i-primenenie/
- https://ismith.ru/metal/markirovka-vysokolegirovannoj-stali/
